applied fracture mechanics

where DK is the damage parameter given byStructural Reliability Improvement Using In-Service Inspectionfor Intergranular Stress Corrosion of Large Stainless Steel Piping 337Log v C C D(7)2 14 15 KD K C 12 Log f 2 environment C 13K(8)where K is stress intensity factor,C12, C13 and C15 are constants and C14 is normallydistributed.For AISI 304 austenitic stainless steel, C12 = 0.8192, C13 = 0.03621 and C15 = 1.7935; mean valueof C14 = -3.1671 and standard deviation of C14 =0.7260 (Harris et al., 1992).From a probabilistic failure analysis of austenitic nuclear pipe against SCC, Priya in (Priya Cet al., 2005) inferred that expressions given in PRAISE for computation of stress intensityfactors for modeling crack propagation need modification. This modification has beenintroduced by using well-accepted expressions given in ASM Handbook (American Societyof Materials, 1996), and with modified PRAISE approach, stochastic propagation of stresscorrosion cracks with time has been studied. The expression for the stress intensity factor fora part-through crack in a hollow cylinder is given byK SF a(9)where S is the tensile or bending stress (assumed to be the value of applied stress in thestudy), F is a function of a/b, R/h, and a/h, where a is the crack depth, b is half the cracklength, R is the inner radius of the cylinder, and h is the wall thickness. The values of F arecalculated for length and depth directions separately using the tables given in ASMHandbook (American Society of Materials, 1996). Since these factors are applicable forvalues of a/b less than 1.0, the expression for stress intensity factor for part-through cracks ina finite plate is used when a/b becomes greater than 1.0. This expression is given bya K Fs (10) Q where Q is the crack shape parameter which depends on a/b ratio and Fs is a function ofa/b, a/h, and b/W and such that2 4a aFsM1M2 M3 G1ffw(11) h hwhere12 M 11.0 0.04 b b (12) aa